This invention relates to a method for positioning a conveying mechanism for conveying semiconductor wafers or the like, in particular to a method for quickly positioning a conveying system.
In general, a system for manufacturing semiconductor devices includes combined various processing chambers. A conveying mechanism is provided between two of the chambers and/or between one of the chambers and a cassette for containing many semiconductor wafers, in order to convey the wafers automatically. The conveying mechanism has a conveying arm that is able to expand, contract, rotate and move vertically. The conveying arm is adapted to move horizontally to a predetermined convey-position in order to convey a wafer to a predetermined position.
In the case, it has to be avoided that the conveying arm interferes or collides with another element while the conveying arm is moving. In addition, the conveying arm has to appropriately receive a wafer that has been placed on a predetermined position, convey the wafer to an objective position and pass the wafer to an appropriate position precisely.
Thus, a xe2x80x9cteaching operationxe2x80x9d is performed. By the teaching operation, important positions such as a position in a moving path of the conveying arm to pass the wafer can be memorized as position coordinates in a controlling unit such as a computer that controls operations of the conveying arm.
The teaching operation is performed for almost all of positional relationships involved with receiving and passing of a wafer, such as a positional relationship between the conveying arm and a cassette container, a vertical positional relationship between the arm and the cassette for taking the wafer and a positional relationship between a stage of a load-lock chamber and the arm. Then, respective positional coordinates can be memorized. Each of driving systems incorporates an encoder or the like for determining a driving position thereof.
In detail, at first, a position in a moving path of the conveying arm is set as an absolute standard. Then, position coordinates are calculated from designed values with respect to positions in the entire system for which teaching operations should be performed. The calculated position coordinates are inputted into and memorized in the controlling unit as provisional position coordinates. In the case, the respective provisional position coordinates are inputted allowing for such a predetermined margin that the conveying arm does not collide with another element.
Next, the conveying arm is operated based on the respective provisional position coordinates. When the conveying arm reaches a vicinity of the teaching standard position, a control mode is switched into a manual mode. Then, for example in a state wherein a fork of the conveying arm and the wafer are in contact with each other, an operator performs a manual operation to make a center position of the fork coincide with a center position of the wafer while the operator watches the state from a lateral side with his or her naked eyes. After the centers coincide with each other, the coordinates are memorized in the controlling unit as accurate and appropriate position coordinates. The conventional teaching operation is performed according to the above steps. The teaching operations are performed manually and with operator""s naked eyes for each of the teaching standard positions.
In the above conventional positioning method, the conveying arm is delicately positioned by made to rotate, expand and/or contract. Thus, there is a problem that the positioning needs very long time.
In addition, because of personal difference between the operators performing the teaching operations, accuracy of the positioning may be uneven. Furthermore, in a case wherein the fork and/or the arm is repaired or replaced, the above steps of positioning operation by teaching have to be repeated again, which may cause very long time loss.
This invention is intended to solve the above problems. The object of this invention is to provide a method for positioning a conveying system that can precisely and efficiently position a teaching standard position.
The invention is a method for positioning a conveying system including; a conveying arm having: a conveying arm body that is able to contract, expand, rotate and move vertically, and a holding portion provided at a tip portion of the conveying arm body for holding an object to be conveyed, a moving mechanism for causing the conveying arm to move, at least one container stage disposed in a moving area of the holding portion for placing a cassette container that can contain a plurality of objects to be conveyed in a tier-like manner, a direction-position positioning unit having: a rotation standard stage disposed in the moving area of the holding portion, and a position and posture detector for detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage, and a controlling unit that can control entire operations, wherein the holding portion is positioned with respect to a standard position,
the method comprising; a step of inputting respective provisional position coordinates of an orienter teaching standard position that is a predetermined position on the rotation standard stage and a container teaching standard position that is a predetermined position in the cassette container placed on the container stage, into the controlling unit in advance, a step of conveying and placing an object to be conveyed precisely positioned with respect to and held by the holding portion onto the rotation standard stage, according to a control based on the provisional position coordinates of the orienter teaching standard position, a step of detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage by the position and posture detector, a step of making appropriate position coordinates by amending the provisional position coordinates of the orienter teaching standard position based on the detected eccentric volume and the detected eccentric direction, a step of conveying and placing an object to be conveyed precisely positioned with respect to the container teaching standard position onto the rotation standard stage, according to a control based on the provisional position coordinates of the container teaching standard position, a step of detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage by the position and posture detector, and a step of making appropriate position coordinates by amending the provisional position coordinates of the container teaching standard position based on the detected eccentric volume and the detected eccentric direction.
According to the feature, correct appropriate position coordinates can be obtained, by conveying an object to be conveyed manually precisely positioned with respect to and held by the holding portion of the conveying arm to the direction-position positioning unit or by taking an object to be conveyed manually precisely positioned with respect to each of the teaching standard positions by the conveying arm and conveying the object to the direction-position positioning unit by the conveying arm, and by detecting an eccentric volume and an eccentric direction of the object.
In a real operation, the controlling unit causes the conveying arm to move based on the appropriate position coordinates. Thus, the conveying arm can be positioned quickly and precisely without consuming long time like a conventional positioning. In addition, there is no personal difference in the positioning operation, that is, precise positioning can be always achieved not dependently on ability of the operator.
It is preferable that: the moving mechanism has a guide rail on which the conveying arm can slide, and the provisional position coordinates include an X-coordinate along the guide rail, an R-coordinate being a contraction or expansion volume of the conveying arm body, a xcex8-coordinate being a rotation volume of the conveying arm body and a Z-coordinate being a vertical movement volume of the conveying arm body.
Preferably, a load-lock chamber in which a vacuum can be formed is arranged in the moving area of the holding portion, the load-lock chamber having therein a object-to-be-conveyed stage for placing the object to be conveyed, and the method further comprises: a step of inputting provisional position coordinates of a load-lock teaching standard position that is a predetermined position on the object-to-be-conveyed stage, into the controlling unit in advance, a step of conveying and placing an object to be conveyed precisely positioned with respect to the load-lock teaching standard position onto the rotation standard stage, according to a control based on the provisional position coordinates of the load-lock teaching standard position, a step of detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage by the position and posture detector, and a step of making appropriate position coordinates by amending the provisional position coordinates of the load-lock teaching standard position based on the detected eccentric volume and the detected eccentric direction.
According to the feature, precise positioning can be achieved with respect to the load-lock teaching standard position of the load-lock chamber.
Preferably, the load-lock chamber is connected to a transferring chamber, the transferring chamber is connected to a processing chamber having therein a susceptor for placing the object to be conveyed, the transferring chamber has a transferring arm having: a transferring arm body that is able to contract, expand and rotate, and a second holding portion provided at a tip portion of the transferring arm body for holding an object to be conveyed, a nick is formed at a peripheral portion of the object to be conveyed, the position and posture detector can detect a position of the nick of the object to be conveyed, and the method further comprises: a step of inputting provisional position coordinates of a susceptor teaching standard position that is a predetermined position on the susceptor, into the controlling unit in advance, a step of conveying and placing an object to be conveyed precisely positioned with respect to the susceptor teaching standard position to the load-lock chamber by the transferring arm, according to a control based on the provisional position coordinates of the susceptor teaching standard position, a step of conveying and placing the object to be conveyed placed in the load-lock chamber onto the rotation standard stage by the conveying arm, a step of detecting an eccentric volume, an eccentric direction and a position of the nick of the object to be conveyed placed on the rotation standard stage by the position and posture detector, a step of making appropriate position coordinates by amending the provisional position coordinates of the susceptor teaching standard position of the transferring arm based on the detected eccentric volume and the detected eccentric direction, and a step of causing the controlling unit to memorize the detected position of the nick as a positioning direction of the direction-position positioning unit.
According to the feature, the transferring arm can be precisely positioned with respect to the susceptor teaching standard position of the processing chamber.
In the case, preferably, the number of the provided load-lock chambers is two, and the object-to-be-conveyed stage is arranged in each of the two load-lock chambers.
According to the feature, a conveying system that may convey the object to be conveyed through either one of the two load-lock chambers can be precisely positioned.
Alternatively, the processing chamber may be connected to the load-lock chamber without providing the transferring chamber.
In the case, the load-lock chamber is provided as a pair with the processing chamber, and the object-to-be-conveyed stage is arranged in each of the load-lock chambers.
In addition, preferably, the conveying arm has a mapping arm that can take map information of the object or objects to be conveyed in the cassette container, the mapping arm being horizontal to the conveying arm body, a light-emitting unit that can emit a level-detecting light in a horizontal direction is arranged in the moving area of the holding portion, a light-receiving unit that can receive the level-detecting light emitted from the light-emitting unit is arranged, and the method further comprises: a step of causing the conveying arm to relatively vertically move in a vicinity of the light-emitting unit by using the level-detecting light emitted from the light-emitting unit in the horizontal direction as a standard, and calculating distance information between the conveying arm body and the mapping arm, a step of taking the map information for each of cassette containers, and a step of making appropriate position coordinates by amending the provisional position coordinates about the X-coordinate, based on the distance information and the map information.
According to the feature, more appropriate position coordinates, whose Z-coordinate also has been amended, can be obtained.
In addition, preferably, the method further comprises after the step of inputting the respective provisional position coordinates: a step of roughly positioning the respective teaching standard positions, and a step of setting position coordinates obtained by roughly positioning as new provisional position coordinates.
According to the feature, the provisional position coordinates set based on designed values can be replaced with relatively more accurate position coordinates obtained by being roughly positioned. However, the roughly positioning operation is unnecessary when the provisional position coordinates set based on the designed values are accurate to some extent.
Furthermore, preferably, the method further comprises: a step of conveying and placing an object to be conveyed precisely positioned with respect to and held by the holding portion onto the rotation standard stage, after the holding portion or the conveying arm body has been repaired or replaced, a step of detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage by the position and posture detector, and a step of making new appropriate position coordinates by amending R-coordinates and xcex8-coordinates of all the appropriate position coordinates of the conveying arm, based on the detected eccentric volume and the detected eccentric direction.
According to the feature, in a case wherein the holding portion or the conveying arm body has been repaired or replaced, amendment of an R-coordinate and a xcex8-coordinate of a teaching standard position can be used for all the teaching standard positions of the conveying arm. Thus, all the appropriate position coordinates can be simply and quickly amended regarding the R-coordinate and the xcex8-coordinate of the conveying arm, to make new appropriate position coordinates.
Alternatively, the method further comprises: a step of conveying and placing an object to be conveyed precisely positioned with respect to and held by the holding portion onto the rotation standard stage, after the holding portion or the conveying arm body has been repaired or replaced, step of detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage by the position and posture detector, and a step of making new appropriate position coordinates by amending X-coordinates and R-coordinates of all the appropriate position coordinates of the conveying arm, based on the detected eccentric volume and the detected eccentric direction.
According to the feature, in a case wherein the holding portion or the conveying arm body has been repaired or replaced, amendment of an X-coordinate and an R-coordinate of a teaching standard position can be used for all the teaching standard positions of the conveying arm. Thus, all the appropriate position coordinates can be simply and quickly amended regarding the X-coordinate and the R-coordinate of the conveying arm, to make new appropriate position coordinates.
Furthermore, preferably, the method further comprises: a step of causing the conveying arm to relatively vertically move by using a level-detecting light emitted in a horizontal direction as a standard, and calculating distance information between the conveying arm body and a mapping arm, after the holding portion or the conveying arm body has been repaired or replaced, a step of taking map information for each of cassette containers, and a step of making appropriate position coordinates by amending Z-coordinates of all the appropriate position coordinates of the conveying arm, based on the distance information and the map information.
According to the feature, in a case wherein the holding portion or the conveying arm body has been repaired or replaced, all the appropriate position coordinates can be simply and quickly amended regarding the Z-coordinate, to make new appropriate position coordinates.
Furthermore, preferably, the method further comprises: a step of conveying and placing an object to be conveyed precisely positioned with respect to and placed on the second holding portion to the load-lock chamber by the transferring arm, after the second holding portion or the transferring arm body has been repaired or replaced, a step of conveying and placing the object to be conveyed placed in the load-lock chamber onto the rotation standard stage by the conveying arm, a step of detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage by the position and posture detector, and a step of making new appropriate position coordinates by amending all the appropriate position coordinates of the transferring arm, based on the detected eccentric volume and the detected eccentric direction.
According to the feature, in a case wherein the second holding portion or the transferring arm body has been repaired or replaced, amendment of an R-coordinate and a xcex8-coordinate of a teaching standard position can be used for all the teaching standard positions of the transferring arm. Thus, all the appropriate position coordinates can be simply and quickly amended regarding the X-coordinate and the R-coordinate of the transferring arm, to make new appropriate position coordinates.
Furthermore, preferably, during an operation of the conveying system after the appropriate position coordinates has been made, the conveying system is adapted to detect a positional deviation of the holding portion that is generated during the operation, by calculating coordinates of a special portion of the conveying arm at any time by using the position and posture detector of the direction-position positioning unit or a level detecting unit in the moving area.
According to the feature, during a usual operation, it is easy to detect how much positional deviation of the conveying arm is generated. In the case, the special portion of the conveying arm may be a light-penetrable window formed at the conveying arm, or may be a special edge portion of the conveying arm.
In addition, one conveying arm can have two conveying arm bodies and two holding portions, which can be operated independently. In the case too, the above invention can be applied. In addition, one transferring arm can have two transferring arm bodies and two second holding portions, which can be operated independently. In the case too, the above invention can be applied.
Furthermore, preferably, the method further comprises: a step of conveying and placing an object to be conveyed precisely positioned with respect to and held by the holding portion onto the rotation standard stage, according to a control based on the appropriate position coordinates of the orienter teaching standard position, a step of detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage by the position and posture detector, and a step of confirming the appropriate position coordinates of the orienter teaching standard position based on the detected eccentric volume and the detected eccentric direction.
Furthermore, preferably, the method further comprises: a step of conveying and placing an object to be conveyed precisely positioned with respect to each of the respective teaching standard positions onto the rotation standard stage, according to a control based on the appropriate position coordinates of each of the teaching standard positions, a step of detecting an eccentric volume and an eccentric direction of the object to be conveyed placed on the rotation standard stage by the position and posture detector, and a step of confirming the appropriate position coordinates of each of the teaching standard positions based on the detected eccentric volume and the detected eccentric direction.